Fuel injection valve for internal combustion engines

ABSTRACT

An injection valve which injects fuel directly into the inlet valve for a cylinder in an internal combustion engine comprises a piston which is reciprocable in the chamber of a cylinder member from a neutral position to a retracted position to thereby admit into the chamber a metered quantity of fuel, and thereupon from neutral to an extended position to thereby inject such quantity of fuel into the inlet valve. The piston is moved by an electromagnetic drive which receives signals from an electronic control circuit.

United States Patent [72] Inventors [wan Komaroff Ludwigsburg;

Hans Zeller, Doefiingen; Gerhard llaug, Stuttgart; Ulrich Strelcher,Bamberg; Walter Schlagmuller, Butthard, all of Germany [21] Appl. No.15,437

[22] Filed Mar. 2, 1970 [45 Patented Nov. 30, 1971 [73] Assignee RobertBosch GmbH Stuttgart, Germany [32] Priority Feb. 28, 1969 [33] Germany[54] FUEL INJECTION VALVE FOR INTERNAL COMBUSTION ENGINES 9 Claims, 4Drawing Figs. [52] US. Cl 123/32, 123/32 FA, 123/32 JV, 123/139 E,123/139 AK, 239/585 [51] Int. Cl F02d 5/00 [50] Field oiSearch 123/32,32

' EA, 32 AB, 139 E; 239/88,89,90,533,585

[56] References Cited UNITED STATES PATENTS 3,131,866 5/1964 Cummings etal. 239/90 2,530,128 11/1950 Mashinter 239/88 X 2,918,911 12/1959 Guiot123/32 EA Primary Examiner- Laurence M. Goodridge Attorney-Michael S.Striker ABSTRACT: An injection valve which injects fuel directly intothe inlet valve for a cylinder in an internal combustion enginecomprises a piston which is reciprocable in the chamber of a cylindermember from a neutral position to a retracted position to thereby admitinto the chamber a metered quantity of fuel, and thereupon from neutralto an extended position to thereby inject such quantity of fuel into theinlet valve. The piston is moved by an electromagnetic drive whichreceives signals from an electronic control circuit.

FUEL INJECTION VALVE FOR INTERNAL COMBUSTION ENGINES BACKGROUND OF THEINVENTION The present invention relates to internal combustion enginesin general, and more particularly to improvements in engines of the typewherein the fuel is injected into the cylinders. Still moreparticularly, the invention relates to improvements in valves whichatomize and inject metered quantities of fuel into the cylinders of aninternal combustion engine, especially to valves whose operation iscontrolled by electronically regulated electromagnetic drive means.

Recently developed electronic control circuits which regulate theadmission of fuel to the cylinders of an internal combustion enginerender it possible, in theory, to control the admission of fuel with ahigh degree of precision so that the cylinders receive an optimummixture of fuel and oxygen under all operating conditions. However, itwas found that the presently available valves which atomize and injectfuel are not entirely satisfactory. As a rule, such valves are actuatedby electromagnets which receive signals from the electronic controlcircuit and inject fuel to the suction manifold. The valves are openedin response to energization of associated electromagnets and remain openfor intervals whose length is determined by the control circuit to thusinsure injection of predetermined quantities of fuel per unit of time.It is preferred to inject atomized fuel directly into the inlet valvesfor the cylinders. This brings about the advantage that the engineoperates in the same way as if the fuel were injected directly into thecylinder chambers without, however, necessitating pressurization of thefuel to the same extent as in engines where the fuel is actuallyinjected into the cylinder chambers proper. Thus, the injection valveswhich direct fuel into the inlet valves need not pressurize the fuel tothe same degree as in engines where the orifices of injection valvesdischarge directly into the chambers of the corresponding cylinders.

Another advantage of engines wherein the injection valves admit fuelinto the inlet valves rather than into the cylinder chambers proper isthat the mist formed by nonevaporated minute fuel particles is caused toenter the cylinder chambers and produces a desirable cooling action.

All such advantages were duly recognized in the art; however, thepresently known injection valves are incapable of insuring that arequisite amount of fuel is injected during the intervals when theassociated inlet valves for the cylinders remain open, especially if theengine operates at a high speed so that the intervals during which theinlet valves remain open are very short. Attempts to overcome suchdrawbacks of presently known injection valves include an increase inpressurization of fuel which, in turn, creates additional problemswithout invariably insuring that a desired quantity of fuel is injectedinto an inlet valve during the short interval when the inlet valve isopen.

SUMMARY OF THE INVENTION An object of the invention is to provide anovel and improved fuel injection valve which is constructed andassembled in such a way that it can invariably inject a desired quantityof fuel into an inlet valve during the intervals when the inlet valve isopen.

Another object of the invention is to provide an injection valve whichcan insure timely injection and atomization of fuel even if the fuel issupplied thereto at a relatively low pressure.

A further object of the invention is to provide an injection valve whoseoperation can be regulated by presently known electronic controlcircuits and which can be used with equal advantage in many types ofelectronically regulated internal combustion engines.

The invention is embodied in a fuel injection valve for internalcombustion engines, particularly for direct injection of fuel into theinlet valve for a cylinder in an internal combustion engine. Theinjection valve comprises a cylinder member defining a chamber andprovided with fuel admitting opening means and fuel-discharging orificemeans, a piston reciprocably received in the chamber, and electric drivemeans (preferably including an electromagnetic drive which is regulatedby the electronic control circuit for the engine) operative to move thepiston from a neutral position to a second position whereby the pistoneffects admission of fuel by way of the opening means, and from theneutral position to a third position whereby the piston expels the thusadmitted fuel by way of the orifice means.

The injection valve preferably further comprises a sealing device whichis operatively connected with the piston and seals the orifice meanswhen the piston dwells in the neutral or second position as well asduring movement of the piston between neutral and second positions.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved fuel injection valve itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain specific embodiments withreference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic axial sectionalview of a fuel injection valve which embodies the invention;

FIG. 2 is a diagram showing a curve representing the signals which areused to effect movements of the piston to second position in which thepiston permits entry of fuel into the cylinder member;

FIG. 3 is a similar diagram showing a curve representing those signalswhich are used to effect movements of the piston in a direction to expelfuel from the cylinder member; and

FIG. 4 is a diagram showing the sequence of movements and duration ofdwells of the piston in neutral, second and third positions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1,there is shown a fuel injection valve which comprises a cylinder member13 defining a cylinder chamber 13a, a piston 12 which is reciprocable inthe chamber 13a, and an electromagnetic drive 10 which serves toreciprocate the piston 12 with reference to the cylinder member betweena neutral position a, a retracted or second position b and an extendedor third position 0. The movable armature 14 of the electromagneticdrive 10 is operatively connected with the piston 12 by a rod or shaft11. The arrows 15 indicate those forces which are generated by theelectromagnetic drive 10 to move the piston 12 to the retracted positionb. The forces indicated by arrows 16 are applied to movethe piston 12 tothe extended position c. The numeral 29 denotes an electronic controlcircuit which supplies signals to the drive 10.

The piston 12 is formed with an internal compartment 12a and with anaxial bore 17 which accommodates the intermediate portion or stem 18 ofa sealing device having a conical head 19 and a plunger 21 which isaccommodated in the compartment and is biased toward the bottom surface12b of the compartment by a helical spring 23 which reacts against aninternal shoulder of the piston 12. The numeral 22 denotes a clearance(having a width eta) which develops between the plunger 21 and bottomsurface 1211 when the piston 12 dwells in the illustrated neutralposition a.

The cylinder member 13 is formed with a fuel admitting opening 24 whichis sealed by the peripheral surface of the plunger 12 when the latterdwells in the neutral position a, and with a divergent fuel dischargingorifice 20 which is sealed by the head 19 when the piston 12 assumes theneutral position a or moves between the positions a, b or dwells in theposition b. The maximum width eta of the clearance 22 depends on thedimensions of the valve.

The operation of the valve will be described with reference FIGS. 2, 3and 4. The diagram of FIG. 2 indicates the electric signals Jd which arefurnished to the drive by the circuit 29 and serve to effect movement ofpiston 12 from the neutral position a to the retracted position b(suction stroke of the piston). The diagram of FIG. 3 illustrates theelectric signals Js which are transmitted to the drive 10 and serve toeffect movement of the piston 12 from the neutral position a to theextended position c (injection stroke of the piston). The minimumduration of a signal J'd is :1 and its maximum duration is lmatr. Theduration ts of each signal .Is is the same; such duration is selected insuch a way that it is less than the minimum duration of opening of theassociated inlet valve 30 (FIG 1) which admits fuel into the chamber ofthe corresponding cylinder in the internal combustion engine.

FIG. 4 shows a diagram which represents movement of the piston 12between and its dwells in the positions a, b and c. When the piston 12dwells in the retracted position b, it exposes the discharge end of theopening 24 and permits admission of a metered quantity q of fuel intothe chamber 130. It is assumed that the rate of fuel admission isconstant; therefore, when the piston 12 dwells in the position b for aninterval ll, it permits the chamber 130 to receive a quantity gl' offuel. If the electronic control circuit 29 which regulates the length ofsignals Jd changes the length of such signals from r! to lmax, thechamber 13a receives a quantity gmax of fuel. The length of signals .11!is regulated in dependency on one or more factors which influence theoperation of the internal combustion engine, such as the pressure in theintake manifold, the pressure of atmospheric air, the position of thegas pedal, and/or others.

The fuel which is admitted into the chamber 130 in response to movementof the piston 12 to the retracted position b remains in the cylindermember 13 until the piston moves to the extended position 0, i.e., untilthe drive 10 receives a signal Js.

When the piston 12 dwells in the neutral position a, its peripheralsurface seals the discharge end of the opening 24. The spring 23 isstressed sufficiently to insure that the head 19 of piston 12. Suchsealing, position of the head 19 is illustrated in FIG. 1.

As stated above, the transmission of a signal M to the drive 10 resultsin movement of the piston 12 to the position b whereby the cylindermember 13 receives a fuel quantity gl if the length of the signal Jdequals t. After elapse of such interval, the piston 12 returns to theneutral position a under the action of the spring 23 and its peripheralsurface seals the opening 24 to entrap the quantity g] in the chamber130. The drive 10 gl receives a signal I: substantially simultaneouslywith opening of the inlet valve 30, and such signal causes the piston 12to move to the extended position 0 and to dwell in this position for theinterval is. During the initial stage of movement of piston 12 from theposition a to the position c, the front end face 12: of the pistoncompresses the fuel in the chamber 130 because the bottom surface 12bmoves toward tom surface 12b engages and pushes the plunger 21 towardthe chamber 130. The orifice then discharges atomized fuel directly intothe open inlet valve 30. On termination of the interval IS, the piston12 returns to the neutral position a to thereby return the head 19 intosealing engagement with the seat in the orifice 20. This takes place assoon as the bottom surface 12b moves away from the plunger 21, i.e., assoon as the width of the clearance 22 exceeds zero. During returnmovement of the head 19 to the sealing position of FIG. 1, the piston 12draws air through the orifice 20 and the quantity of such air depends onthe maximum width of the clearance 22. If such clearance is substantial,the amount of air which is sucked into the chamber 13a is small becausethe head 19 can reassume its sealing position at an earlier stage ofmovement of the piston from the position 0 to the position a,

It is possible to increase the width of the clearance 22 to such anextent that the bottom surface 12b is never in contact with the plunger21. The head 19 then moves to open position exclusively under thepressure of fuel in the chamber while the piston 12 moves from theposition 0 toward the position c. The head 19 then returns to sealingposition as soon as the piston 12 leaves the position c.

It was found that the improved fuel injection valve operates in a mostsatisfactory way if the orifice 20 is immediately adjacent to the intakeend of the inlet valve 30. As stated above, the inlet valve 30 shouldopen not later than when the piston 12 begins to move toward theposition c and should remain open at least during the interval is.

The numeral 31 denotes in FIG. 1 a throttle or flow restrictor installedin a conduit which supplies fuel to the opening 24.

The improved fueI injection valve can be provided with means foradjusting the bias of the spring 23 and/or for regulating the width ofthe clearance 22 to thus regulate the exact moment when the head 19opens or seals the orifice 20 during axial movement of the piston 12,Le, during movement between the positions a and c.

An important advantage of our valve is that the entire interval betweentwo successive movements of the piston 12 to extended position 0 isavailable for admission of fuel into the chamber 13a. Such interval islong enough to insure that the chamber 130 receives a desired quantityof fuel even if such fuel is admitted at a relatively low pressure,Moreover, suction which is created in the chamber 13a while the piston12 moves to the retracted position b promotes the inflow of fuel by wayof the opening 24. Therefore, the engine which utilizes the improvedinjection valves can employ a relatively simple and inexpensive fuelpump which merely subjects the fuel to a pressure sufficing to admitinto the chamber 13a a desired quantity of fuel which is a function ofthe length of the interval rI-llmax) during which the piston 12 dwellsin the retracted position b, The flow restrictor 31 in the fuel supplyconduit for the opening 24 insures that the quantity of fuel admittedinto the cylinder member 13 is independent of the pressure in chamber13a while the piston 12 moves toward and dwells in the position [2.Similar results can be achieved by providing the cylinder member 13 withan auxiliary opening which is temporarily sealed by the piston 12 and isexposed at least during a portion of the suction stroke of piston 12 toinsure that the pressure in the chamber 13a cannot unduly influence theinflow of fuel. The control circuit 29 shows in FIG. 1 is of the typedisclosed, for example, in the German Pat. No. 1,100,377.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of our contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A fuel injection valve for internal combustion engines, particularlyfor direct injection of fuel into the inlet valve for a cylinder in aninternal combustion engine, comprising a cylinder member defining achamber and provided with a fuel admitting opening means and fueldischarging orifice means; a piston reciprocably received in saidchamber; a device for sealing said orifice means; connecting means foroperating said device by said piston; drive means operative to move saidpiston from a neutral position in which said piston is sealing saidopening means and the device is sealing said orifice means, to aretracted second position whereby the piston effects admission of fuelby way of said opening means into said chamber, and from said neutralposition to an extended third position whereby the piston operates saiddevice to open said orifice means and expels the previously admittedfuel by way of said orifice means from said chamber.

2. A fuel injection valve as defined in claim 1, wherein said drivemeans comprises an electromagnetic drive having a movable portionoperatively connected with said piston.

3. A fuel injection valve as defined in claim 1, wherein said device forsealing said orifice means opens said orifice means in response torising fuel pressure in said chamber during movement of said piston fromneutral to third position.

4. A fuel injection valve as defined in claim 1, said device having afirst portion coupled to said piston with a predetermined clearancewhich is reduced to zero during movement of said piston from neutral tothird position and a second portion which exposes said orifice means inresponse to such reduction of said clearance while said piston continuesto move toward said third position.

5. A fuel injection valve as defined in claim 4, wherein said devicefurther comprises an intermediate portion disposed between said firstand second portions thereof and wherein said orifice means diverges in adirection away from said piston, said second portion comprising asubstantially conical head which enters and seals said orifice means notlater than when said piston effects admission of fuel into said chamber,said piston having an internal compartment and a bottom surface in saidcompartment, said first portion of said device comprising a plungerreceived in said compartment and further comprising means for biasingsaid plunger toward said bottom surface, said clearance being providedbetween said plunger and said bottom surface in neutral position of saidpiston and while said head seals said orifice means.

6. A fuel injection valve as defined in claim 5, wherein said piston isfurther provided with 'an axial bore connecting said compartment withsaid chamber and said intermediate portion of said device is a stemwhich is slidably guided in said bore.

7. A fuel injection valve as defined in claim 1, wherein said cylindermember is provided with auxiliary opening means which is sealed fromsaid chamber during predetermined stages of movement of said piston.

8. A fuel injection valve as defined in claim 1, further comprisingmeans for throttling the flow of fuel into said chamber by way of saidopening means.

9. A fuel injection valve as defined in claim 1, wherein said drivemeans is arranged to respectively maintain said piston in said secondand third positions for first and second intervals of time and whereinthe duration of said first intervals at least equals the duration ofsaid second interval.

1. A fuel injection valve for internal combustion engines, particularlyfor direct injection of fuel into the inlet valve for a cylinder in aninternal combustion engine, comprising a cylinder member defining achamber and provided with a fuel admitting opening means and fueldischarging orifice means; a piston reciprocably received in saidchamber; a device for sealing said orifice means; connecting means foroperating said device by said piston; drive means operative to move saidpiston from a neutral position in which said piston is sealing saidopening means and the device is sealing said orifice means, to aretracted second position whereby the piston effects admission of fuelby way of said opening means into said chamber, and from said neutralposition to an extended third position whereby the piston operates saiddevice to open said orifice means and expels the previously admittedfuel by way of said orifice means from said chamber.
 2. A fuel injectionvalve as defined in claim 1, wherein said drive means comprises anelectromagnetic drive having a movable portion operatively connectedwith said piston.
 3. A fuel injection valve as defined in claim 1,wherein said device for sealing said orifice means opens said orificemeans in response to rising fuel pressure in said chamber duringmovement of said piston from neutral to third position.
 4. A fuelinjection valve as defined in claim 1, said device having a firstportion coupled to said piston with a predetermined clearance which isreduced to zero during movement of said piston from neutral to thirdposition and a second portion which exposes said orifice means inresponse to such reduction of said clearance while said piston continuesto move toward said third position.
 5. A fuel injection valve as definedin claim 4, wherein said device further comprises an intermediateportion disposed between said first and second portions thereof andwherein said orifice means diverges in a direction away from saidpiston, said second portion comprising a substantially conical headwhich enters and seals said orifice means not later than when saidpiston effects admission of fuel into said chamber, said piston havingan internal compartment and a bottom surface in said compartment, saidfirst portion of said device comprising a plunger received in saidcompartment and further comprising means for biasing said plunger towardsaid bottom surface, said clearance being provided between said plungerand saId bottom surface in neutral position of said piston and whilesaid head seals said orifice means.
 6. A fuel injection valve as definedin claim 5, wherein said piston is further provided with an axial boreconnecting said compartment with said chamber and said intermediateportion of said device is a stem which is slidably guided in said bore.7. A fuel injection valve as defined in claim 1, wherein said cylindermember is provided with auxiliary opening means which is sealed fromsaid chamber during predetermined stages of movement of said piston. 8.A fuel injection valve as defined in claim 1, further comprising meansfor throttling the flow of fuel into said chamber by way of said openingmeans.
 9. A fuel injection valve as defined in claim 1, wherein saiddrive means is arranged to respectively maintain said piston in saidsecond and third positions for first and second intervals of time andwherein the duration of said first intervals at least equals theduration of said second interval.